1. Field of the Invention
The present invention relates to a fuel cell system, and more particularly, to a heat exchanger for a fuel cell system that has a fuel cell stack and a reformer.
2. Description of the Related Art
A fuel cell system generates electricity through an oxidation reaction of hydrogen contained in fuel and through a reduction reaction of oxygen. In more detail, a fuel cell system can be configured to generate electrical energy through an oxidation reaction of hydrogen generated by reformed fuel, and through a reduction reaction of oxygen that is separately supplied.
The fuel cell system includes a reformer, a fuel supply apparatus, and an oxygen supply apparatus. The reformer reforms a fuel to a reformed fuel from which hydrogen is generated. The reformer supplies the hydrogen to a fuel cell. The fuel supply apparatus supplies a fuel to the reformer, and an oxygen supply apparatus supplies oxygen to the fuel cell.
In the fuel cell system, high-temperature steam is generated through reduction reaction of oxygen, and is typically discharged during operation of the fuel cell. If this steam is directly discharged into air, which is at a relatively low temperature, the steam is condensed into water as the steam contacts the air. If the fuel cell system is installed in an application system without any means to manage the water produced during the operation of the fuel cell system, water will flow from the fuel cell system, and will drip into the application system The water will cause damages in the application system, which is not desirable to the application system. Therefore, a fuel cell system requires a type of heat exchanger to condense steam generated in the fuel cell into water, and to reuse the water, thereby preventing the water from dripping from the fuel cell system.
An application system having a fuel cell system is generally configured to include a heat exchanger having a fan that is disposed in a separate housing. The heat exchanger having a fan, however, is bulky, and has limitations in making the application system compact. The fuel cell system having the bulky heat exchanger cannot be used in portable electronic devices.
Furthermore, if a fan is included in a heat exchanger, additional electrical energy is required to drive the fan. As a result, in addition to power needed to drive the fuel cell system, separate power (parasitic power) is required to drive the fan, thereby deteriorating the performance and efficiency of the overall fuel cell system. There is also problems of noise the fan generates during the operation.